HPLC determination of sulfadiazine residues in coho salmon (Oncorhynchus kisutch) with confirmation by liquid chromatography with atmospheric pressure chemical ionization mass spectrometry

High-performance liquid chromatography and postcolumn derivatization with fluorescamine were used to determine sulfadiazine (SDZ) residues in muscle and skin from salmon dosed with Tribrissen. Determinations in the fish ranged from 0.2 to 21600 ng of SDZ/g; in each fish tested, the concentration of SDZ in the skin was at least twice that in the muscle. Liquid chromatography with atmospheric pressure chemical ionization mass spectrometry (LC-APCI/MS) was used to confirm SDZ residues. In-source collision induced dissociation was optimized to produce a mass spectrum containing the protonated molecule and four fragment ions. Sulfadiazine was confirmed in muscle fortified with 10 ng of SDZ/g and in muscle from fish dosed with SDZ by the accurate agreement of ion intensity ratios generated from muscle compared with those generated from SDZ standard injections.